1. Field of the Invention
The present invention relates to an image converter, an image reproducer, an image conversion/reproduction system, and a program.
2. Description of the Related Art
Recently, image display devices such as TVs have progressed remarkably, and various types of devices with a capability of high resolution or high pixel count display have been developed and used in ordinary households. Display devices mounted on mobile terminals such as cellular phones, etc. have also come with upgraded capabilities.
However, cellular phones, etc. are more preferable if they are smaller and lighter, and hence usually mounted with a CPU, a memory device, etc. that are lower-powered than those mounted on TVs, etc. Therefore, when transferring image data having a high image quality that is created for reproduction on TVs, DVD recorders, etc., to cellular phones, etc. to reproduce the image data on the cellular phones, etc., it is necessary to convert or degrade the image quality of the image data to an image quality matching the capabilities of the cellular phones, etc., i.e., to a lower image quality. Degrading is to lower, for example, resolution, bit rate, etc. Degrading can compress the overall size of the image data and reduce the decoding load.
For example, Unexamined Japanese Patent Application KOKAI Publication No. 2001-45436 discloses a digital broadcast receiver that converts received image data to image data adapted to an external device connected to it.
Conventional data conversion techniques degrade uniformly all the frames that constitute high quality image data (e.g., MPEG data). Therefore, cellular phones, etc. will reproduce image data whose image quality has been lowered uniformly for all the frames. Image data that has been recorded at a high image quality can only be viewed at a low image quality when users reproduce the image data on a cellular phone, etc. If image data that has been degraded uniformly throughout its frames contains information with a very small size, e.g., small-sized letters, users cannot understand it. On the other hand, if image data with a high image quality uniformly is reproduced on a cellular phone, etc., a large load is imposed on the device, which therefore may not be able to reproduce the image data smoothly or store the image data.